Jump to main content
Jump to site search

Issue 39, 2014
Previous Article Next Article

A DFT study of the structures, stabilities and redox behaviour of the major surfaces of magnetite Fe3O4

Author affiliations

Abstract

The renewed interest in magnetite (Fe3O4) as a major phase in different types of catalysts has led us to study the oxidation–reduction behaviour of its most prominent surfaces. We have employed computer modelling techniques based on the density functional theory to calculate the geometries and surface free energies of a number of surfaces at different compositions, including the stoichiometric plane, and those with a deficiency or excess of oxygen atoms. The most stable surfaces are the (001) and (111), leading to a cubic Fe3O4 crystal morphology with truncated corners under equilibrium conditions. The scanning tunnelling microscopy images of the different terminations of the (001) and (111) stoichiometric surfaces were calculated and compared with previous reports. Under reducing conditions, the creation of oxygen vacancies in the surface leads to the formation of reduced Fe species in the surface in the vicinity of the vacant oxygen. The (001) surface is slightly more prone to reduction than the (111), due to the higher stabilisation upon relaxation of the atoms around the oxygen vacancy, but molecular oxygen adsorbs preferentially at the (111) surface. In both oxidized surfaces, the oxygen atoms are located on bridge positions between two surface iron atoms, from which they attract electron density. The oxidised state is thermodynamically favourable with respect to the stoichiometric surfaces under ambient conditions, although not under the conditions when bulk Fe3O4 is thermodynamically stable with respect to Fe2O3. This finding is important in the interpretation of the catalytic properties of Fe3O4 due to the presence of oxidised species under experimental conditions.

Graphical abstract: A DFT study of the structures, stabilities and redox behaviour of the major surfaces of magnetite Fe3O4

Back to tab navigation

Supplementary files

Publication details

The article was received on 05 Feb 2014, accepted on 08 May 2014 and first published on 12 May 2014


Article type: Paper
DOI: 10.1039/C4CP00529E
Citation: Phys. Chem. Chem. Phys., 2014,16, 21082-21097
  • Open access: Creative Commons BY license
  •   Request permissions

    A DFT study of the structures, stabilities and redox behaviour of the major surfaces of magnetite Fe3O4

    D. Santos-Carballal, A. Roldan, R. Grau-Crespo and N. H. de Leeuw, Phys. Chem. Chem. Phys., 2014, 16, 21082
    DOI: 10.1039/C4CP00529E

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements